In many fantasy settings, a race of mushroom creatures are often encountered. They may or may not look humanoid but still have the biology of fungi.

My question is how. How can a mushroom be mobile, how do the muscles and various systems work (lets do repository, circulatory and digestive systems) and how can they sense the world! They are mushrooms for crying out loud!

Please note, I have heard that given the right conditions, a mushroom my evolve to uproot itself (somehow), walk (somehow) to a new batch of rotten wood and evolve from there, but the part i'm confused is the biology of such an organism.

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    $\begingroup$ I'd like to meet a mushroom man. He'll certainly be a fun-guy. $\endgroup$ Commented Nov 25, 2019 at 21:19
  • $\begingroup$ Ha ha ha ha...ha $\endgroup$
    – Seraphim
    Commented Nov 25, 2019 at 21:27
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    $\begingroup$ Piece of information: mushrooms are not complete organisms. They are the fruiting bodies of fungi. The fungus itself is very very much bigger than the mushroom, and it is mostly underground. In the right conditions, it produces mushrooms, which are structures on which the spores grow. Confusing a mushroom with the entire fungus is like confusing a cone with the fir tree. As for the "biology of mushroom creatures" I am not certain that I understand the question. What is of interest? Their basic biochemistry? The same as ours. Nutrient transport? Quite tricky, based on citoplasmic streaming... $\endgroup$
    – AlexP
    Commented Nov 25, 2019 at 22:34
  • $\begingroup$ There are the "grey caps" from Jeff Vandermeer's Ambergris. $\endgroup$
    – Spencer
    Commented Nov 25, 2019 at 23:50

2 Answers 2


In some respects, the biology of the fungi family is more closely related to the animal kingdom than plants; in reality though it's more of a hybrid or even a separate division in its own right - another point in the triangle of terrestrial biology.

There is not a huge set of fungal species that in fact lives in a multi-cellular construct and those that do, procreate via spores. This is an important point because this evolutionary design makes it far less likely that the larger species of fungus need to be ambulatory. They merely spread through spores, which has been a very successful strategy for them but means that their success is heavily reliant on the next generation at every turn.

So, for your mushroom men to evolve, firstly you need an environment that encourages the fungus into a longer life cycle, but still has challenging environmental changes. Animals can take advantage of larger territories, exploiting the change in one region (say an apple tree ripening its fruit) at one point and then when that is exhausted, moving on to another (say salmon swimming upstream in a near by creek). They have far less children when compared to a fungus' spore release, but have longer lives of higher utility and variability. Evolutionarily speaking, you need the same drivers to be present with fungi to make your mushroom men happen.

Of course, you have another issue as well; senses. Animals formed a sense of smell, and later taste, touch, vision & hearing so that they could negotiate and navigate their environment when they became ambulatory. As a consequence, they could seek out food, opportunity, and sense danger in time to avoid it. Brains are useful for processing all this sensory input, but not necessary. All you need is a central nervous system of some kind for rudimentary instinctive responses to the environment to make all that work. The trouble is, even a central nervous system is a complex design to encode in DNA. Mushrooms at their core are simple constructs and evolution prefers simplicity where it can get away with it so sensory organs evolving in mushrooms are only going to happen in response to becoming ambulatory.

Brains are a whole other matter and the likelihood of two competing animal like constructs, one the animal kingdom we currently know and one based on fungal structures growing and evolving in parallel, competing for the same resources over hundreds of millions of years, is unlikely. One would get wiped out by the other at some point during which resources are scarce and the fittest evolutionary model succeeds the other.

But; it's possible. Imagine (if you will) that fungi come up from the waters first, alongside plants, and that animal progression to land is delayed even a little. If the fungi evolved into an ambulatory species on land directly, their senses would be evolved perfectly for the land. They would have a distinct advantage over traditional animals, particularly in sight, in the first instance because fish and amphibian eyes are designed for a water medium; it's going to take time for animal eyes to adapt to use on land and in an atmospheric environment. But, animals would eventually have an advantage through the fact that they are used to predators and a lack of safety (not really any places to hide in the open ocean) so they are going to be more aggressive and better at evading predators in the main. In such an environment, it's possible that when the land on earth is split into two main continents, the fungal life succeeds on one, and animal life on the other. As they split and merge, certain species of both die out, but for the most part species of each also survive.

I must stress this is all pure speculation, but it's possible. What is needed? Well, firstly a driving advantage in the environment towards a longer, ambulatory life where spores (say) can't be both light AND carry all the genetic information required for replication. Secondly, time. Lots of time to hone and refine the new ambulatory fungus and its senses in a manner that allows it to function efficiently on a land environment.

Finally though, your mushroom creatures may be close to animals, but its HIGHLY unlikely that they will be men with highly intelligent brains. I doubt they would be able to talk with you. Again its possible, but brain power takes a massive amount of energy to maintain and I suspect that evolution isn't going to support two different species with equivalent brain power on one planet - humans for instance are just too good at wiping out all their threats and I suspect that your mushroom men would be the same, meaning at some point that fight would come to a head and you'd be down to one again soon enough.


It's a symbiotic mechanism

I'm citing a bit of a frame challenge here. The biology on fungi is interesting, but there's nothing within it which is designed for anything resembling that of the Animal Kingdom. Fungi biology does not have anything similar to that of muscles, respiratory systems, nerves, anything of that nature. You can alter the fungi to have similar processes to us, but at that point it's not really 'the biology of fungi' and more 'the biology of fungi which is basically the biology of the Animal Kingdom'.

Which means that if we want to keep this as close to fungi biology as possible, it's best for us to cheat and say that mushroom men are in fact half men and half mushroom. Essentially, an organic life form and a fungus have come together and formed a symbiotic relationship. Most of the creature is a fungus-layer skin, which protects the organism and digests the food that it comes across. The rest of the organism is an animal that wears it, a small animal which is responsible for a neural network that interacts with the fungus and gives rise to the Animal Kingdom exclusive abilities, like muscles and eyes. When these animals give birth, they also give the baby mushroom creature some of the parent's fungus coat. And thus, most of the animal is a complex fungus layer, but its around a framework of organic animal.

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    $\begingroup$ You might get to this point by a more symbiotic relationship with a cordyceps-like fungus. You could even have it so that most of the creature is an animal, but the brain, parts of the head (so they look mushroomy), and maybe bits of digestive tract (to help with the symbiosis bit) are fungal. $\endgroup$ Commented Feb 20, 2020 at 8:49

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